Air Bags
Try them on!
I was always told to make sure they fit properly. If your backpack is uncomfortable, you will be more likely to not wear it...
BCA uses compressed air, easy to fill @ a scuba shop, paintball shop etc.
I believe these come with a couple spare 0-rings...
ABS uses nitrogen, and there is a charge in the handle.
These are more expensive to fill as they puncture the canister, and the trigger needs to be replaced as well. These need to be sent in to ABS to refill so (correct me if I'm wrong) no matter if you buy a replacement canister at an ABS dealer or personally send yours in, you foot the bill for the hazmat shipping.
All in all these are roughly 100 bucks to refill when said and done...
I personally went with the ABS Vario Bag. Fits me really well!
My friend went with the BCA Float 30, he preferred the fit of it!
May not be the info you are looking for but just my .02.
Hope you find the bag that is right for you!